import java.util.Arrays;
import java.util.Random;

public class SC
{
    public static void main(String[] args)
    {
        int randomNum;
        int[] b = new int[20];
        for (int i = 0; i<20; i++)
        {
            b[i] = 0;
        }
        for (int i = 0; i<20; i++)
        {
            for (int j = 0; j<=i; j++)
            {
                randomNum = 1+(int) (Math.random()*100);
                if (b[j]==randomNum)
                {
                    break;
                }
                if (j==i)
                {
                    b[j] = randomNum;
                    System.out.println("第"+(j+1)+"个整数是"+b[j]);
                }
            }
        }
        sort(b);
        
    }
    
    public static void sort(int[] array)
    {
        for(int i=0;i<array.length;i++)
        {
            for(int j=i+1;j<array.length;j++)
            {
                if(array[i]>array[j])
                {
                    int temp=array[i];
                    array[i]=array[j];
                    array[j]=temp;
                }
            }
        }
        System.out.println(Arrays.toString(array));
    }
}

------解决方案--------------------
你的随机是要打算生成不重复的数？
Java code
    public static void main(String[] args)
    {
        int i=0;
        int[] b = new int[20];
        Set set=new HashSet();
        while(set.size()<20)
        {
            int randomNum=1+(int) (Math.random()*100);
            if(set.add(randomNum))
            {
                b[i++]=randomNum;
            }
        }
        sort(b);
        
    }
    
    public static void sort(int[] array)
    {
        for(int i=0;i<array.length;i++)
        {
            for(int j=i+1;j<array.length;j++)
            {
                if(array[i]>array[j])
                {
                    int temp=array[i];
                    array[i]=array[j];
                    array[j]=temp;
                }
            }
        }
        System.out.println(Arrays.toString(array));
    }

------解决方案--------------------
 for(int i=0;i<array.length;i++)
       {
           for(int j=i+1;j<array.length;j++)
           {
               if(array[j]>array[j+1])
               {
                   int temp=array[j];
                   array[j+1]=array[j];
                   array[j]=temp;
               }
           }
       }
       System.out.println(Arrays.toString(array));


------解决方案--------------------
import java.util.Random;
public class BubbleSort{
public static void main(String[] args){
Random rand=new Random();
int[] RandomNum=new int[20];
for(int i=0;i<RandomNum.length;i++){
RandomNum[i]=rand.nextInt()%100;
  }
bubbleSort(RandomNum);
System.out.println("按升序：");
for(int i=0;i<RandomNum.length;i++){
 System.out.print(RandomNum[i]+" ");